Furnace having housing wall shielding furnace packing



Jan, 21, 1969 T.KRAUS ETAL 3 3 FURNACE HAVING HOUSING WALL SHIELDING FURNAQE PACKING Filed Dec. 14, 1966 United States Patent 18,167 65 US. C]. 13-20 6 Claims Int. Cl. H!) 3/62 ABSTRACT OF THE DISCLOSURE A closed evacuable furnace includes a substantially cylindrical furnace housing which is closed at its bottom end,and has an opposite end with a flanged opening for receiving a cover member. The cover member is of hoodshaped configuration and includes a flange around the shoulder portion of the hood which engages with the flange of the housing to form a vacuum-tight closure. The cylindrical housing includes a side wall with a fitting for connecting the apparatus to an evacuation pump. The hood construction includes a cylindrical wall portion which extends inwardly into the housing at a spaced location from the interior walls thereof and provides a shield around a furnace heating area defined between the housing bottom and the interior of the substantially cylindrical wall of the cover. A heater is mounted in the housing and extends upwardly into the cover.

BRIEF SUMMARY OF THE INVENTION The invention deals with furnaces which are maintained at a pressure which is below atmospheric pressure so that sealing of the various housing parts of the furnace using conventional sealing elements such as plastic gaskets or rubber gaskets presents a great problem. Such sealing materials must not be overheated since they tend to become brittle and unusable when subjected to excessive heat. In addition, the sealing materials will give off gases upon excessive heating if a high vacuum is maintained within the furnace which interfere with the heating processes to be carried out.

A further diflicult problem is encountered in the construction of such high temperature vacuum furnaces in the connection of the pump to the furnace. This requires not only additional gaskets for the pump nipple and any valves which must also be protected against overheating, but also the radiant heat flowing into the pump nipples may cause evaporation of the lubricants and the fuels used in the oil vapor pumps and any existing oil traps and penetration of the vapors get into the furnace heating area. This, of course, will mean a loss of the lubricants or fuels in the pump, but also the gases and vapors which will form will have a deleterious effect on the materials being treated in the furnace. In analytical apparatus, an undesired gas source is additionallyproduced.

It is known to provide protective radiation plates which are fixed in such furnaces at various locations, but such a construction hinders cleaning of the furnace and makes it diflicult to assemble the furnace parts. In addition, such arrangements are not effective in protecting the pump nipple or piping connection against the penetration of dirt particles.

In accordance with the present invention, there is provided a furnace constructed with at least two interengageable furnace wall parts which are sealed in respect to each other and with at least one of the parts being fashioned to extend downwardly into the other part and around an area which is to be subject to the heating inorder to shield the surrounding area and particularly the packing Patented Jan. 21, 1969 "ice between the parts and the associated pump connections, etc., against the high temperatures. In the preferred arrangement, the closed evacuable furnace is provided with a fixed housing part which carries a pump connection and which also supports a hood-shaped cover which in the closed position of the furnace protrudes into the fixed part and shields the associated packing connections between the parts against high temperatures which exist within the shielded part during operation.

In the preferred form of the invention, the furnace includes a bottom housing portion which is of doublewalled construction with means for circulating a cooling fluid through the space between the double walls and a central cylinder connection for connecting a pipe nipple to an evacuating pump which supports a flange portion of a substantially dome-shaped double-walled top part or cover having means for circulating a cooling fluid in the space between the walls, the cover being such that it extends downwardly into the bottom portion and provides a central furnace heating area and shields the remaining portions of the housing from the high temperatures of the heating area.

Accordingly, it is an object of the invention to provide a furnace which is connected to a pump for evacuating the furnace to maintain a pressure within the furnace below atmosphere wherein a housing portion is formed of a substantially cylindrical configuration in the manner of a hood providing a shield between a high temperature heating area of the furnace and the surrounding portion of the furnace in order to shield the packing elements in the surrounding portion of the furnace against high temperatures.

A further object of the invention is to provide a furnace which is adapted to operate at pressures below atmospheric pressures and which includes a connection for connecting the furnace to an evacuation pump wherein the bottom portion of the furnace and the top portion are of double-walled construction and have means for circulating a cooling liquid therethrough, with at least one of these portions being of substantially U-shaped configuration and forming a hood within the central portion of the furnace protecting the surrounding areas including the packing and the pump connection from the high temperatures within the central portion of the furnace.

A further object of the invention is to provide a furnace which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The only figure of the drawing is a transverse sectional view of a furnace constructed in accordance with the invention.

DETAILED DESCRIPTION Referring to the drawing in particular, the invention embodied therein comprises a furnace structure generally designated 20 which includes a double-walled 'bottom portion generally designated 3, a double-walled hood-shaped cover or top portion generally designated 4, and an intermediate cylindrical portion or flange member 1 having a nipple or connecting flange 2 for connecting the furnace to a pump (not shown) for evacuating the air therefrom in order to provide operation within the interior of the furnace at a predetermined vacuum. A cooling fluid is circulated through an inlet opening 3a and a discharge opening 3b of the bottom portion and through an inlet opening 4a and a discharge opening 411 of the top portion. Combination heating electrodes and supports 6, 6 extend through the bottom wall 3 and are connected to a heating element 5 to supply the necessary current for the operation thereof. The exterior of the supports 6, 6 are connected to respective electrical current supply lines 7, 7.

The cover portion 4 advantageously includes a cylindrical portion 8a which is closed by a glass cover 8 with the interposition of suitable packing 8b. Inspection of the operating conditions within the furnace and particularly within a shielded chamber portion 22 defined centrally within the cover 4 may be viewed through the window 8.

The cover 4 is also provided with a flange extension 24 which is seated on an internal flange formation 26 of the intermediate portion 1 and a suitable sealing ring 9 is interposed in a groove 26a of the flange 26. An external flange 28 is formed at the lower end of the intermediate portion and it seats on a flange Portion 30 of the bottom member 3. A sealing ring 10 is disposed within a groove 30a of the flange portion 30. The nipple 2 is provided with a flange 2a having an annular groove 2b for accommodating a sealing ring 11 for interposition between it and a flange of the connecting member of a pump (not shown).

A feature of the inventive construction is that the cover member 4 is designed as a hood and it extends downwardly through the intermediate portion 1 and into the bottom portion 3 sufliciently to provide a complete shield of the chamber 22 at which the high temperatures of the operating furnace will be concentrated. As clearly seen in the drawing, it will thus be evident that the cover 4 provides a protection of the pump (not shown) which is connected to the nipple 2 as well as all of the gasket elements 9, 10 and 11 which will be shielded against radiant heat and against the vapors issuing upon heating of the material to be treated in the chamber portion 22.

The heating apparatus 5 and the connections 6,6 for supplying suflicient current for operation thereof is of conventional design and is not set forth in detail.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. An evacuable heating furnace comprising a double wall substantially cylindrical bottom portion, a heater supported on said bottom portion, terminal means for said heater extending through said bottom portion, an intermediate cylindrical portion having a nipple connection for connecting said furnace to an evacuation pump, a hoodshaped cover portion having wall portions of double wall construction extending downwardly into said furnace through said intermediate portion and a portion of said bottom portion and surrounding said heater, said hood shaped cover, said intermediate portion and said bottom portion each having flanges which are interengaged and which are sealed by packing, said cover defining a high temperature reaction furnace area therewithin and shielding the packing and said pump nipple connection against the high temperatures surrounding said heater.

2. An evacuable heating furnace comprising a double wall substantially cylindrical bottom portion, a heater supported on said bottom portion, an intermediate cylindrical portion having a nipple connection for connecting said furnace to an evacuation pump, a hood-shaped cover having wall portions of double wall construction extending downwardly through said intermediate portion and a portion of said bottom portion and defining an unobstructed substantially cylindrical wall surrounding said heater, said cover, said intermediate portion and said bottom portion each having flanges which are interengaged and which are sealed by packing to form a vacuum-tight closure, said cover defining an unobstructed substantially cylindrical high temperature reaction furnace area therewithin opening downwardly to said bottom portion and shielding said pump nipple against the high temperature surrounding said heater.

3. An evacuable heating furnace according to claim 2, including means for circulating a cooling fluid through the space between the double walls of said bottom portion and said cover.

4. An evacuable heating furnace according to claim 2, wherein said hood shaped cover includes a central cylindrical window portion having an opening at its upper end, and a glass cover closing the opening of said cylindrical window portion and permitting viewing of said heater from the top of said cover.

5. An evacuable heating furnace according to claim 2, including a pair of electrical terminal elements extending through the double wall of said bottom portion, and means for circulating a cooling medium in the space between said bottom portion double walls for cooling said bottom portion and said terminals.

6. A closed evacuable furnace including a cylindrical housing portion having a closed end and an opening at an opposite end with a sealing flange therearound and a side wall with a fitting for a pump connection, and a hoodshaped cover, said cover having an upper shoulder with an exterior outwardly extending flange disposed in sealing engagement with said sealing flange of said housing portion, said cover having a cylindrical wall extending downwardly from said shoulder and into said cylindrical housing portion below said pump fitting and terminating in an interior substantially circular unobstructed opening, said cover cylindrical wall being adapted to surround the material to be treated and to shield said pump fitting, and a heater mounted in said housing portion within said cover cylindrical wall.

References Cited UNITED STATES PATENTS 2,266,735 12/1941 Berghaus et al. 13--3l 2,826,624 3/1958 Reese et al l3--33 XR 2,971,039 2/1961 Westeren 1320 XR ROBERT R. SCHAEFER, Primary Examiner.

MORRIS GINSBURG, Assista nt Examiner.

U.S. Cl. X.R. 

